1. Field of the Invention
This invention is in the field of medical devices and methods for correcting spinal column deficiencies.
2. Description of the Prior Art
One of the most perplexing problems to the pediatric orthopedic surgeon or spine surgeon has been paralytic kyphosis of the spine, particularly the meningomyelocele. The reason for the severe problems is the early age of onset, decubitus ulcers, inability to brace, difficulty in surgically correcting the kyphosis without substantially shortening the trunk and difficulty maintaining the correction. Kyphosis of the spine is a selfperpetuating problem. In the meningomyelocele or paralytic kyphosis the individual's paravertebral muscles are ineffectual and the abdominal muscles increase or perpetuate the kyphosis. Due to the early onset and the early fixation of the spine and perpetual pressure sores, surgeons have attempted to correct this problem early. Some have advocated removal of the apical vertebral body of the kyphosis and fusion which shortens the spine. The deformity recurs rapidly because the fusion is not long enough and does not correct the lordosis that occurs above and below the kyphosis. Thus, the spine has to be straightened from the apex of the upper lordosis to the apex of the lordosis below the kyphotic area. Due to the fact that this deformity occurs so early in life it necessitates that something be done early and the attack has to be anteriorly. The absence of posterior elements of the spine and the cancellous bone of the vertebral body makes the conventional internal fixation devices useless. Therefore, a device was designed to satisfy the following criteria: (1) Correct the deformity without shortening of the spine but depend on the ligamentus structures for support; (2) Maintain the correction until spinal fusion has occurred from the apex of the upper lordosis to the apex of the lower lordosis across the kyphosis; (3) If the soft tissue (arteries, veins or abdominal wall) will not allow immediate correction, a simple staged procedure can be used to gradually correct the kyphosis.
Some devices have been provided for straightening or supporting the spine. For example, U.S. Pat. Nos. 2,702,031 issued to H. L. Wenger and 3,242,922 issued to C. B. Thomas disclose supporting devices mountable to the pelvic bone extending upwardly to support the spinal column. Another approach has been to replace one or more natural vertebrae with an artificial device such as disclosed in U.S. Pat. No. 3,426,364 issued to W. V. Lumb. Another approach disclosed in U.S. Pat. No. 2,774,350 issued to C. S. Cleveland, Jr. provides tension to a vertebrae in order to correct the deficiency. Other devices such as disclosed in U.S. Pat. Nos. 1,950,799 issued to C. P. Jones and 3,693,616 issued to Roaf et al disclose devices for securing bones together. Another device disclosed in U.S. Pat. No. 3,565,066 issued to Robert Roaf discloses an implant for causing the displaced vertebrae to be drawn toward a rigid member. The method disclosed in U.S. Pat. No. 3,648,691 issued to William Lumb provides an appliance for use in bridging one or more diseased or damaged vertebrae.